Field of Application
The present invention relates to a control apparatus for an internal combustion engine, and in particular to a control apparatus for controlling combustion in a compression-ignition type of engine.
Background Technology
Technology is known for calculating the latent heat of vaporization, low-order calorific value and density of a fuel oil (referred to in the following simply as a fuel), based on detecting the Cetane number of the fuel, as described in Japanese patent publication No. 2012-132411. Also, as described in that patent, it is known to calculate the amount of fuel to be injected in each pilot injection that is executed by a compression-ignition engine, based on the calculated values of latent heat of vaporization, low-order calorific value and density of the fuel utilized by the engine. It is proposed in that way to control the amount of each pilot injection such that the calorific value of each injection is equal to the value obtained when using a standard grade of light oil as fuel. The calorific value of each pilot injection is to be thereby made independent of the type of fuel actually used.
However even if the calorific value of each pilot injection amount is controlled to be constant, there is a danger that cooling losses may be increased and increased amounts of soot etc., may be produced when certain types of fuel are utilized. This is due to concentration of the combustion region, within the combustion chamber of each cylinder of the engine, close to the walls of the combustion chamber. There is thus a need for improvements of the technology described in the above patent.